1. Field of the Invention
The application relates to a handset device, particularly a handset device that uses a conductive strip to change a current distribution on a ground plane of a system.
2. Description of Related Art
Currently, telecommunications of the public have entered the age of wireless communications, so handset devices are used more and more often in different sorts of occasions and are more and more diverse, such as cell phones, smart phones, multimedia players, personal digital assistants, satellite positioning devices, and so on. Different sorts of small-sized handset devices have been gradually developed and have become necessary electronic products in the daily lives of people.
During the development of wireless communications, the Federal Communications Commission (FCC) further presented rules of Hearing Aid Compatibility (HAC) to define the compatibility and safety between the hearing aids and many kinds of communication equipment. Under rules of HAC, cell phone manufacturers are obligated to limit the electromagnetic interference (EMI) of cell phones below a threshold, wherein the EMI includes electric fields and magnetic fields interfering with and affecting the endurance of hearing aids. Normal HAC does not just seek to solve the effects of electric fields on hearing aids; interferences by magnetic fields are not negligible either. It orders that the M3 Rating must be achieved. That is to say, the electric field value is less than 84.1 V/m and the magnetic field value is less that 0.25 A/m. In addition, cell phone manufacturers further provided some cell phones that comply with the rules of HAC, so that audio frequency signals are transmitted to hearing aids using electromagnetic induction functions of telecoils.
With respect to the realization of cell phones complying with rules of HAC, present technologies mostly increase distances between antennas and receivers, so that the limitation of EMI regulated by the rules of HAC is complied with. Increases in the distances between the antennas and the receivers must be realized by changing the positions where the antennas are disposed. However, present technologies mostly can only change the positions of the antennas by using external antennas, as provided in U.S. Pat. No. 7,342,545 B2, for example. Thereby, not only the exterior design of cell phones is restricted, but also development towards miniaturization and applications of cell phones is affected.